Involvement of retinoblastoma protein in dibutyryl cyclic AMP-induced growth inhibition of the human hepatoma cells PLC/PRF/5

Abstract

The role of retinoblastoma (RB) protein in cyclic AMP (cAMP)-induced growth inhibition was investigated with the human hepatoma cells PLC/PRF/5 in culture. Dibutyryl cAMP (DBcAMP) inhibited DNA synthesis of the PLC/PRF/5 cells, and this DBcAMP-induced growth inhibition was partially abrogated by addition of antisense oligodeoxynucleotides (ODN) to RB mRNA. The antisense ODN itself had no significant effect on the growth. DBcAMP also inhibited the phosphorylation of RB proteins. These findings suggest that RB is a mediator of the DBcAMP-induced growth inhibition of PLC/PRF/5 cells.